JPH11270415A - Egr valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR valve in which a play of a specified gap is set in a power transmitting system to transmit the torque of a motor to the valve, a complete shutting of the valve is ensured, and the gap is made simply adjustable to be accurately set. SOLUTION: A motor shaft 31 to make straight motion with the rotation of a rotor 21 installed in a motor case 2 is positioned confronting a valve shaft 14 furnished in a valve body 1. A play S of a specified spacing is set between the motor shaft 31 and valve shaft 14 when the rotor 21 is held in one of the rotational limit position inside the motor case 2 and the valve 11 is shut at the valve body 1, and a guide bushing 13 for stopping the motor shaft 31 from rotating is furnished on a partition 3, which is held pinchedly between the valve element 1 and motor case 2 with rotational adjustability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an EGR (Exhaust Gas Recirculation) provided in an exhaust gas recirculation system.
) Valve.

[0002]

2. Description of the Related Art Conventionally, this type of EGR valve has
For example, one described in JP-A-7-332168 is known.

[0003] Such an EGR valve is designed to open and close the valve by the torque of a stepping motor such as a PM type, and a power transmission mechanism for transmitting the torque of the motor to the valve as the force to open and close the valve is provided by the power transmission mechanism. There is no play in the transmission system. Therefore, in order to make the valve closing position coincide with the rotor origin of the motor, EG
It has been necessary to interpose spacers of various thicknesses at the joint between the body of the R valve and the case of the motor, and to adjust the so-called shim between the joints between the body and the case.

[0004]

However, in such an EGR valve, the coupling distance between the body of the EGR valve and the case of the motor is adjusted by shim so that the closed position of the valve and the origin of the rotor of the motor are adjusted. The task of matching was extremely troublesome. Moreover, if the valve closing position changes over time due to wear of the valve or seat,
The closing position of the valve may deviate from the origin of the rotor of the motor, so that the valve may not be able to be sufficiently closed, or accurate opening / closing control of the valve may not be possible.

An object of the present invention is to provide a power transmission system for transmitting the rotational force of a motor to a valve with a play at a predetermined interval,
It is possible to realize accurate opening / closing control by easily adjusting the interval of the play after compensating for the complete closing of the valve.
It is to provide a GR valve.

[0006]

According to a first aspect of the present invention, there is provided a valve body accommodating a valve which is urged in a valve closing direction and which can be opened and closed by an axial movement of a valve shaft, and is rotationally driven by a motor. A motor case accommodating a rotating body that can be coupled to the valve body, a stopper provided on the motor case to regulate a rotation limit position in one rotation direction of the rotating body, and a stopper provided on the motor case. A spring for urging the rotator in the one rotation direction, screwed to a rotation center of the rotator and facing the valve shaft in the axial direction, the valve is closed, and the rotator is A motor shaft that is separated from the valve shaft by a predetermined distance when restricted to a rotation limit position in one direction, and that the motor shaft is prevented from rotating. One axially to permit movement, characterized in that a circumferentially adjustable in position mounted is the guide member about the axis of the motor shaft relative to the motor case.

According to a second aspect of the present invention, in the first aspect, the rotating body is a rotor of a DC motor.

According to a third aspect of the present invention, in the first or second aspect, the position is sandwiched between the valve body and the motor case so as to be adjustable in a circumferential direction around the axis of the motor shaft. A partition is provided, and the guide body is provided in the partition.

[0009] The invention according to claim 4 is the invention according to claims 1 to 3.
Wherein the motor case is provided with a sensor for detecting a rotational position of the rotating body.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a valve body in which an exhaust gas passage interposed in an exhaust gas recirculation system is formed. The valve 11 moves upward as shown in FIG. The gas passage is closed and valve 1
The exhaust gas passage is opened when 1 moves downward and separates from the seat 12. Reference numeral 2 denotes a motor case accommodating the DC motor 20, and reference numeral 3 denotes a partition corresponding to the lower opening of the motor case 2. The connection structure of the valve body 1, the motor case 2, and the partition 3 will be described later. In the motor 20, reference numeral 21 denotes a rotor (rotating body) around which a coil 22 is wound, 23 denotes a yoke provided with a magnet 24, and a rotor shaft 25 having upper and lower shaft portions 25 A and 25 B connected to the center of the rotor 21. Is configured. The upper shaft portion 25A is rotatably supported by the motor case 2 by a bearing 26,
The lower shaft portion 25B is rotatably supported by the partition 3 by a bearing 27. Rotor 2
A commutator 28 is attached to the upper end of 1, and a motor brush 29 provided on the motor case 2 side is pressed against the commutator 28 by a brush spring 30.

Reference numeral 40 denotes a position sensor for detecting the rotational position of the rotor 21. In this embodiment, the position sensor 40 has a form in which the resistance value changes according to the rotational position of the rotor 21. That is, when the resistor layer is formed, the motor case 2
Side, and a brush plate 43 provided with a brush 42 and attached to the rotor shaft 25. The brush 42 moves on the resistor layer of the sensor substrate 41 according to the rotation position of the rotor 21. It comes into sliding contact. The position sensor 40 and the motor brush 29 are connected to a control device (not shown) by the connector terminal 4. 44 is a cover, 45 is packing.

A motor shaft 31 is screwed into the rotor shaft 25.
Is the guide bush (guide body) on the partition 3 side
13 prevents rotation and allows axial movement. Therefore, the motor shaft 31 moves up and down according to the rotation amount of the rotor 21. In this case,
A guide hole 13A having a substantially D-shaped cross section is formed in the guide bush 13 as shown in FIG.
Inside, a lower portion of the motor shaft 31 having a substantially D-shaped cross section is guided so as to be vertically movable.
A stopper plate 33 is attached to the rotor shaft 25, and an outer peripheral portion of the stopper plate 33 and a stopper 2 formed on an inner peripheral surface of the motor case 2.
Due to the contact with A, the rotation limit position in one direction of the rotor 21 is regulated. A spiral spring 32 has an inner end 32A attached to the stopper plate 33 and an outer end 32B attached to the inside of the motor case 2. This spiral spring 32 urges the rotor 21 in one rotation direction, and when the motor 20 is not driven, the stopper plate 33 and the stopper 2A
At the rotation limit position in one direction regulated by
Hold 1 When the rotor 21 is at the rotation limit position in one direction, the motor shaft 31 moves to the upper limit position as shown in FIG. When the rotor 21 is driven to rotate in the other direction, the motor shaft 31 moves downward.

The lower end of the motor shaft 31 faces the upper end of the valve shaft 14 having the valve 11 attached to the lower end. An intermediate portion of the valve shaft 14 has a valve body 1 formed by a guide seal 15 and a guide plate 16.
The guide is movable up and down. 17 is a guide seal cover. Between the spring seat 18 attached to the upper end of the valve shaft 14 and the valve body 1, a coil spring 19 for urging the shaft 14 upward, that is, in the closing direction of the valve 11, is interposed.

At the connecting portion of the valve body 1, the motor case 2, and the partition 3, flanges 1A, 2B, and 3A each having a substantially rectangular plane are formed, and these are connected by a total of four bolts 51. ing. That is, a circular bolt insertion hole 2 </ b> C into which the collar 52 is fitted is formed in the flange portion 2 </ b> B, and the flange portion 3 </ b> A extends over a range of about 30 ° in the circumferential direction around the axis of the motor shaft 31. An elongated hole 3B is formed, and a screw hole 1B for screwing to the bolt 51 is formed in the flange portion 1A.
Each of the flange portions 2B, 3A, and 1A is connected by being screwed into the screw hole 1B through the inside of the second hole 2 and the elongated hole 3B. The elongated hole 3B allows the bolt 51 to slide inside. Therefore, the position of the partition 3 in the circumferential direction can be adjusted in the formation range of the elongated hole 3B.

53 is a spring washer, 54 is a flat washer, 55 is
This is a spacer interposed between the body 1 and the partition 3. Reference numeral 56 denotes an O-ring, and reference numeral 57 denotes a wave washer.

Next, the operation will be described.

The EGR valve configured as described above
It is driven by a so-called torque balance method.

That is, a predetermined return torque is applied in the closing direction of the valve 11 by the coil spring 19, and a variable motor torque is applied in the opening direction of the valve 11 by energizing the DC motor 20 in one direction. The opening and closing of the valve 11 is controlled by the torque balance.
The motor torque is transmitted to the valve 11 when the motor shaft 31 that moves up and down according to the rotation amount of the rotor 21 pushes the valve shaft 14 downward. In the power transmission system for transmitting the motor torque to the valve 11 as described above, a play S at a predetermined interval is formed between the valve shaft 14 and the motor shaft 31 when the valve 11 is closed as shown in FIG. . That is, as shown in FIG. 1, the valve 11 is held at the closed position by the coil spring 19, and the rotor 21 is rotated to one rotation limit position by the spiral spring 32, and the motor shaft 31 is held at the upper limit position. When their shafts 1
A play S is formed between the opposing surfaces 1 and 31.

In the case of such a torque balance driving method, the resolution of the adjustment opening of the valve 11 can be theoretically reduced to infinity by continuously controlling the torque generated by the DC motor 20. Further, the DC motor 20 does not generate a control error due to the step-out phenomenon as in the case of the stepping motor, so that the responsiveness can be improved as compared with the case where the stepping motor is used, and the reliability is also improved. Further, since a play S is formed at a predetermined interval between the valve shaft 14 and the motor shaft 31 in the power transmission system, even if the valve 11 and the seat 12 are worn, the valve 11 is completely removed. Closure will be compensated. The interval between the play S is set to, for example, about 0.2 mm in consideration of their wear.

In controlling the opening and closing of the EGR valve, for example, the sensor output value (voltage) of the position sensor 40 corresponding to the rotational position of the rotor 21 is fed back while
The drive duty of the DC motor 20 can be controlled. Hereinafter, the position of the motor shaft 31 when the rotor 21 is at one of the rotation limit positions is referred to as a “rotor origin”, and when the motor shaft 31 is moved down from the rotor origin by the play S, that is, the valve 11 The position of the motor shaft 31 when the motor starts to open is referred to as a “valve origin”. In controlling the opening and closing of the EGR valve, it is advantageous to set the play S at a constant interval so that the rotor origin and the valve origin have a constant relationship.

The interval of the play S can be adjusted by rotating the partition 3 within the range in which the slot 3B is formed. That is, when the rotor 21 is held at one rotation limit position and the bolt 51 is loosened, by rotating the partition 3, the bush 13 and the motor shaft 31 stopped by the bush 13 are prevented from rotating. It turns, and the screwing position of the motor shaft 31 with respect to the rotor shaft 25 shifts up and down according to the turning direction. As a result, the position of the motor shaft 31 at the rotor origin changes up and down, and the interval of the play S can be adjusted. The partition 3 in FIGS. 2 and 3 is adjusted to a rotation position where the bolt 51 is located at an intermediate position of the elongated hole 3B, and the partition 3 in FIGS. 4 and 5 is such that the bolt 51 is positioned at one end of the elongated hole 3B. It is adjusted to the pivot position where it is located.

When adjusting the interval of the play S, for example, the bolt 51 is loosely tightened to temporarily assemble the valve body 1, the motor case 2, and the partition 3.
The height of the upper end of the valve shaft 15 at the time of closing 1 is measured, and the partition 3 is rotated and adjusted so that the lower end of the motor shaft 31 is adjusted to a position obtained by adding the height to the height by the interval of the play S. Then, the bolts 51 are strongly tightened and assembled. Alternatively, the bolt 51 is loosely tightened, and the valve body 1, the motor case 2, and the partition 3
Is temporarily assembled, the partition 3 is rotationally adjusted while controlling the DC motor 20 and reading the sensor output value of the position sensor 40. For example, the DC motor 20 is operated until the sensor output value reaches a predetermined value, and at that time, the partition 3 is rotationally adjusted so that the lower end of the motor shaft 31 contacts the valve shaft 14, and the motor shaft 31 is moved. Adjust to the valve origin.
After the rotation of the partition 3 is adjusted in this manner, the bolts 51 are strongly tightened and assembled.

[0024]

As described above, according to the first aspect of the present invention, the motor shaft linearly moved by the rotation of the rotating body accommodated in the motor case is opposed to the valve shaft provided on the body. When the rotating body is held at one rotation limit position in the motor case and the valve is closed in the valve body, a predetermined gap is set between the motor shaft and the valve shaft, and the motor shaft is rotated around the motor shaft. By providing a rotatable guide body for stopping, a play at a predetermined interval is set in the power transmission system for transmitting the rotational force of the motor to the valve, and the valve is completely closed and the play is compensated. Can be easily adjusted by the rotation of the guide member, and accurate opening / closing control can be realized.

According to the second aspect of the present invention, the degree of opening of the valve can be controlled with high resolution and high accuracy by using the rotor as the rotor of the DC motor.

According to the third aspect of the present invention, the partition provided with the guide body is sandwiched between the valve body and the motor case so as to be position-adjustable, so that the configuration can be simplified.

According to a fourth aspect of the present invention, the motor case is provided with a sensor for detecting the rotational position of the rotating body, so that the opening degree of the valve is controlled with high accuracy based on the detection signal of the sensor. Can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a view taken in the direction of the arrow II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a view similar to FIG. 2 when a partition is rotated and adjusted.

FIG. 5 is a view similar to FIG. 3 when a partition is rotationally adjusted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve body 1A Flange part 1B screw hole 2 Motor case 2A Stopper 2B Flange part 2C Bolt insertion hole 3 Partition 3A Flange part 3B Long hole 11 Valve 12 Seat 13 Guide bush (guide body) 14 Valve shaft 20 DC motor 21 Rotor (rotation) Body) 31 motor shaft 40 position sensor (sensor) 51 bolt S play

Claims (4)

[Claims] A valve body accommodating a valve which is urged in a valve closing direction and which can be opened / closed by an axial movement of a valve shaft, and a rotator which is rotationally driven by a motor is accommodated and can be coupled to the valve body. A motor case, a stopper provided in the motor case for restricting a rotation limit position in one rotation direction of the rotating body, and a stopper provided in the motor case to bias the rotating body in the one rotation direction. A spring, which is screwed into the rotation center of the rotating body and faces the valve shaft in the axial direction, the valve is closed, and the rotating body is restricted to the rotation limit position in the one direction. A motor shaft that is separated from the valve shaft by a predetermined interval; and a motor shaft that is detented and allowed to move in the axial direction. EGR valve, characterized in that a circumferentially adjustable in position mounted is the guide member about the axis of the motor shaft relative to the case. 2. The EGR valve according to claim 1, wherein the rotating body is a rotor of a DC motor. 3. A partition is provided between the valve body and the motor case so as to be position-adjustable in a circumferential direction about an axis of the motor shaft, and the guide body is provided in the partition. The EGR valve according to claim 1 or 2, wherein: 4. The EGR valve according to claim 1, wherein the motor case includes a sensor for detecting a rotational position of the rotating body.